The forces at work here are gravity and chance alone.
The situation is similar when it comes to roulette, as you do not really have any sort of impact on the movement of the actual ball and the spinning wheel. On the other hand, if you play slots, all you can do is activate the game by inserting money and pulling a lever.
For example, if you play poker, you have a big impact on the game as you can use different strategies, select to use or discard cards, and alike. However, depending on the game there is a varying amount of influence that a player can have over the game. Every gambling game out there is a game of chance.
